De Quincey reckoned a quarter of all human misery was down to toothache; today he might have chosen back pain instead. As well as the discomfort, there is the loss – the squandered potential of people who can't get on with things because of the devil gnawing at their spines. The £480m the NHS spends on surgery is only the start; lost days and incapacity benefits cost many times that. There is little understanding and often a weary sense that little can be done. All hail, then, to the Danish researchers who have isolated a bacterial cause; like Richard Doll, who nailed the link between smoking and cancer while investigating road pollution, the Danes have thought laterally and made it pay off. Better still, they have identified a cure for many cases: antibiotics, the medicine still producing new miracles after 85 years. A society that blunts the drugs' efficacy by over-prescribing and factory farm use will deserve a pain in the back.